Grow Organic Carrots without Carrot Root Fly

One of the biggest challenges for organic gardeners is how to stop garden pests from destroying all your hard work and eating your crop. When growing carrots, the carrot root fly is a really irritating little creature. Its Latin name is Psila Rosae, and it loves your carrots as much as you do.

Psila Rosae is attracted to the crop by the carroty smell. It then lays its eggs on the carrots and it's the creamy yellow maggots which do the damage by tunnelling into the root and leaving nasty brown channels. Sometimes there are so many brown tracks that by the time you've cut them out, there is nothing left, plus, these channels stop carrots from storing well, either in the ground or in storage. The carrot root fly can destroy a whole crop without you even realising until harvest time.

Grow Organic Carrots without Carrot Root Fly

A few of this year's crop, trimmed and ready for the pot.
A few of this year's crop, trimmed and ready for the pot.

 Fortunately, there are several methods you can use to thwart this little ceature without resorting to chemicals.  For many years now I've not had a single piece of carrot root fly damage, either in my professional gardening work or on my allotment, and I'm more than happy to pass my tips on, so that you can grow really good carrots too.

Prepare the Soil - Manure

First of all, you need to prepare the soil. Carrots do not like freshly manured soil. If they come into contact with muck they grow into tortuous shapes in order to get away from it, so unless in your household you particularly like trying to peel tightly corckscrewed carrots with twelve legs, then avoid the manure (however, such carrots may be useful for You Tube, or to send to local newspapers if they are humourous!)

I practise crop rotation on my allotment, so I manure the ground well one year, then grow hungry crops on it, such as beans. The following year I grow carrots on this site, as the beans will have locked nitrogen from the muck into the soil, for the carrots to use.

A little word about manure. Most of my fellow allotment holders buy in a ton of muck, either horse or cow, from local farmers. Firstly it's important to ensure that this is well rotted and has been left to stand for a couple of years; anything fresher will damage crops.

It's also important to consider how organic you want to be. If you are growing commercially, then you have to be very careful. The Soil Association has strict guidelines to follow before it will class your produce as organic. If you're going down this route, then be choosy about your muck and do lots of research about what's acceptable first. Although, you may not use chemicals, the farmer who is providing the manure may use all sorts of chemicals on his land, in the animals' feed, or in vaccinations.

Farmyard manure also brings with it little gifts, such as weed seeds and plants that you really would not welcome. There are clean, organic products out there, but these are generally more expensive. You won't be able to buy a trailer load for £30!

I compromise, by taking the slow route and making my own rich garden compost (that's a whole other hub), and by buying in some organic compost. If you don't have soil that was manured last year, don't tie yourself up in knots, just buy some seed and get started!

Buy Organic Vegetable Seeds

 There is a huge choice in the type of carrot seed available to the gardener, you could buy: yellow carrots, purple carrots, multi-coloured ones, long ones, thin ones, baby ones, round ones, autumn ones, summer ones, carrots that over-winter, carrot seeds on a roll of tape, and even carrots that deter carrot root fly, called, funnily enough Fly Away!

There is less choice if you want to use certified organic seeds, but still more than you can shake a stick at.  If you are happy to just use any seed and then grow the crop without chemicals then fine, choose any type, but if you need to be strictly organic, then only organic seed will do.

Having grown many different types over the years, I've found that the best and sweetest carrots are the plain orange, carrot-shaped carrots, which were bred by the Dutch a couple of centuries ago to celebrate King William of Orange, but you go ahead and have some fun experimenting, then drop me a comment to let me know what's worked for you.

Companion Planting

One way to deter the pesky carrot root fly is to use companion planting. In the autumn each year, I plant rows of garlic (Learn How here), but rather than the usual spacing between rows, I leave a good two feet, then in the spring plant my carrots betwen the rows of garlic. The smell of the garlic really deters the carrot root fly, and although I've experimented with different methods, I've had my best results growing carrots this way.

I'm not a great fan of digging, as it can destroy soil structure and hence allow the leaching away of nutrients. However I am a big fan of mulching and hoeing, so to prepare by seed bed for carrots, I hoe a drill the width of my hoe between each row of garlic, and scatter the carrot seed in this, cover it with a quarter inch of fine soil and give it a good water, then wait.

The Barrier Method

Despite its name, the Carrot Root Fly isn't much of a flier - it's more of a flinger.  It jumps, rather like a flea and flings itself in the general direction of the smell of carrots, which means that it is very easily defeated by a barrier method.  All you need to do is put four posts around your carrots, and attach netting to create a two foot wall (old net curtains from the junk shop are as good as anything, and cheap), then the carrot fly is unable to leap over.  This method tends to work best if your carrots are in a bed, rather than a long row. 

Care of Carrot Plants

 When the carrot seedlings appear, it's important to keep them weed free.  There's no other way to do this except get down there and pull the weeds out by hand, probably once a week when stuff is growing strongly.

Although carrots don't like manure, they appreciate regular feeding.  I tend to use either pelleted chicken manure, or a slow release organic fertilizer, once a month or so, depending on manufacturers instructions.  I rarely water my crops, preferring that they reach out to find water for themselves, however, when seedlings are young, I'll water if we have no rain for three days.  (What am I saying, I live in the West Country, when do we ever go three days without rain!)

Harvesting

 The seed packet will tell you when to plant and harvest your particular variety, but as soon as the carrots look an edible size, I pull some of them to eat as baby carrots, this leaves more room for others to grow on.

When digging carrots up, their aroma is released, hence attracting carrot root fly to your remaining crop, so I crush a few garlic leaves when I'm harvesting the carrots to deter them.

I'm sure my fellow allotmenteers think I'm crazy for this tip, but when I'm harvesting carrots I also burn a little citronella tea-light in a jam jar, again to deter the smell.  I can see the old guys muttering and smirking about this one, but heigh-ho, just like they did when I used porridge oats to deter slugs, but that's really another hub!

Storing Carrots

Unless you are growing an overwintering variety, at the end of the season your remaining carrots will need to be lifted and stored. There are many ways to store veg, again another hub, but you could make some decent soup and freeze it, or simply prepare and freeze the carrots themselves.

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Comments 6 comments

Laurel Oakes profile image

Laurel Oakes 6 years ago

I grew carrots many years ago and they didn't do well at all, so have never attempted it since, but now you've got me thinking!


Georgina_writes profile image

Georgina_writes 6 years ago from Dartmoor Author

Well, they're worth a go, just for the flavour. mine seem to do OK.


Godslittlechild profile image

Godslittlechild 6 years ago

Really good info for next spring's gardening. Thanks!


elayne001 profile image

elayne001 6 years ago from Rocky Mountains

I'm having my first luck with carrots now. I greens look great - now to pick one and see if the carrots are infested. Hope not! Good advice. Aloha!


Georgina_writes profile image

Georgina_writes 6 years ago from Dartmoor Author

Hope not elayne001 - they're sneaky things those root flies!


mistyhorizon2003 profile image

mistyhorizon2003 3 years ago from Guernsey (Channel Islands)

A really great article this one. The only part of it I disagreed on was the height you need to protect your carrots at. Unfortunately 2 foot is not enough because although all the books tell you carrot fly only fly up to about 18", these articles always fail to allow for breezes etc blowing the carrot fly higher. I grow long carrots (amongst others) for exhibition, and the long carrots get grown in oil drums of sand that are over 4 ft high, yet I still get carrot fly damage every year. This year I am building a frame around the containers with polythene sides and an enviromesh top in the hope this will finally prevent the problem once and for all.

All in all a top class hub though, voted up, useful, interesting etc :)

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